Publications by authors named "Markus Rudowitz"
Peroxisomes are involved in a multitude of metabolic and catabolic pathways, as well as the innate immune system. Their dysfunction is linked to severe peroxisome-specific diseases, as well as cancer and neurodegenerative diseases. To ensure the ability of peroxisomes to fulfill their many roles in the organism, more than 100 different proteins are post-translationally imported into the peroxisomal membrane and matrix, and their functionality must be closely monitored.
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- * These ns proteins often have an N-terminal targeting signal that helps them move to specific organelles by stabilizing their translocation intermediates.
- * Researchers can purify early-stage ribosome-associated protein complexes, like those involved in peroxisomal protein import, using plasmids with FLAG-tagged nonstop variants of the cargo protein Fox3p.
Accurate and regulated protein targeting is crucial for cellular function and proteostasis. In the yeast , peroxisomal matrix proteins, which harboring a Peroxisomal Targeting Signal 1 (PTS1), can utilize two paralog targeting factors, Pex5 and Pex9, to target correctly. While both proteins are similar and recognize PTS1 signals, Pex9 targets only a subset of Pex5 cargo proteins.
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- The study investigates the incomplete knowledge of peroxisomal proteins, known as the peroxi-ome, which is essential for grasping their role in cellular metabolism.
- By utilizing high-content microscopy on Saccharomyces cerevisiae, the researchers expanded the known peroxi-ome by about 40% and identified new protein targeting processes within peroxisomes.
- The findings highlight the importance of peroxisomes in gluconeogenesis and their broader implications for organismal health and disease understanding.
Article Synopsis
- Peroxisomes are essential organelles involved in metabolism, and their dysfunction can lead to human diseases; their proper functioning requires the import of specific proteins tagged with a peroxisomal targeting signal (PTS) 1.
- The receptor protein Pex5p is responsible for recruiting these PTS1-proteins for import, and the study identifies 22 phosphorylation sites on Pex5p that may regulate this process post-translationally.
- The research shows that phospho-mimicking mutations in Pex5p decrease its ability to import certain PTS1-proteins, revealing a new mechanism where phosphorylation affects protein binding and cargo import, thereby influencing peroxisomal composition and overall metabolism.
Import of peroxisomal matrix proteins with a type 1 peroxisomal targeting signal (PTS1) in is facilitated by cytosolic import receptors Pex5p and Pex9p. While Pex5p has a broad specificity for all PTS1 proteins independent of the growth conditions, Pex9p is only expressed in fatty-acid containing media to mediate peroxisomal import of the two malate synthases, Mls1p and Mls2p, as well as the glutathione transferase Gto1p. Pex5p-cargo complexes dock at the peroxisomal membrane, translocate their cargo-protein via a transient pore and are recycled into the cytosol for a further round of import.
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